from typing import TypeVar
from tudelft.utilities.immutablelist.Permutations import Permutations
from tudelft.utilities.immutablelist.ImmutableList import ImmutableList
from tudelft.utilities.immutablelist.AbstractImmutableList import AbstractImmutableList
from _ctypes import ArgumentError


E = TypeVar('E')
class AbstractPermutations(AbstractImmutableList[ImmutableList[E]], Permutations[E]) :
	'''
	Abstract base class for Permutations. A Permutation is an ordered sublist of
	a list, possibly with repeated elements.
	
	@param <E> type of the elements
	
	'''

	def __init__(self, lst: ImmutableList[E] ,  n:int):
		'''
		all permutations of a given list, drawing n items from the list
		
		@param lst list to be permuted
		@param n    the number of items to draw from the list. Must be between 0
		            and size of list.
		'''
		if n < 0:
			raise ArgumentError("n<0")
		if lst.size().bit_length() > 31:
			raise ArgumentError(\
				"excessive list size detected for starting a permutation"\
							+ str(lst.size()))
		# protected, not private vars
		self._drawlist:ImmutableList[E] = lst
		self._drawlistsize:int = lst.size()
		self._drawsize:int = n